Lecture 2 Part I Extemporaneous Compounding

Question 0

What is the purpose of extemporaneous compounding?

Answer 0

Allows the compounding pharmacist to work with the patient and the prescriber to customise a medication to meet the patients specific needs.

Question 1

What is extemporaneous compounding?

Answer 1

Medications which are “made from scratch”

Individual ingredients are mixed together in exact strength and dosage required by the patient

Question 2

What is trituration?

Answer 2

Form of icing used when incorporating finely divided insoluble powders or liquids into a base

Question 3

What is trituration performed on?

Answer 3

Glass slab or tile

Question 4

How is liquid incorporated into a base via trituration?

Answer 4

Make a well in centre of base
Pour in small amounts of liquid at a time into the well
Mix in well
Avoid air pockets (these will splash)

Question 5

Why should air pockets be avoided when combining liquid into a base?

Answer 5

Air pockets will splash causing ingredients to go everywhere resulting in loss of product

Question 6

What is levigation?

Answer 6

Form of mixing used for incorporating insoluble course powders into a base

Question 7

What is levigation also known as?

Answer 7

Wet grinding

Question 8

How do you levigate?

Answer 8

Rub down the powder with either a molten base or a semi solid base

Apply shearing force with the flat blade of the spatula against the slab to avoid a gritty product (similar to suppositories)

Question 9

What is the doubling up technique?

Answer 9

Technique used to mix powder to powder,
Powder to semisolid
Or semisolid to semisolid
Especially when one ahi burnt is much smaller than the other

Question 10

What is the doubling up technique done on?

Answer 10

Mortar (powder to powder) or it can be done on a slab

Question 11

How is the doubling up technique done?

Answer 11

Start with small amount of each,
mix thoroughly,
Then double the volume each time as you continue to add an equal amount to what has been mixed

Question 12

How do you add solids and liquids to a semi solid base?

Answer 12

Place weighed semisolid on glass slab
Place all weighed solids in more and mix Or place on glass slab and mix

Use doubling up technique to incorporate solids into base using a spatula

When mixed, make a well in the centre, carefully put in small amounts of liquid and mix within the well or score to mix

Continue until all liquid is well mixed in

Question 13

What is an emulsion?

Answer 13

A thermodynamically unstable system consisting of at least 2 immiscible liquid phases

One phase is dispersed as globules in the other liquid

These are stabilised by an emulsifying agent

Question 14

What are the two types of phases in an emulsion?

Answer 14

Dispersed phase (globules) 
Continuous phase (other liquid)

Question 15

Why is an emulsifying agent needed?

Answer 15

The two phases don’t mix together naturally, so we need an agent to make then stay together

Question 16

What is a disadvantage of a drug in an emulsion form?

Answer 16

Storage may be difficult

Question 17

What do oral emulsions use?

Answer 17

Acacia gum

Question 18

What is the ratio of an emulsion for fixed oils?

Answer 18

4:2:1 (oil:water:gum)

Question 19

What is the emulsion ratio for mineral oils? (Liquid paraffin is a mineral oil)

Answer 19

3:2:1 oil:water:gum

Question 20

What is the ratio for volatile oils?

Answer 20

2:2:1

Question 21

What is the dry gum method for a primary emulsion?

Answer 21

Drain oil into a clean dry flat bottom mortar

Disperse acacia over the oil and mix gently

Add water all at once and stir briskly in one direction until a clicking sound and white frothy primary emulsion forms

Gradually dilute the primary emulsion with vehicle and dissolved ingredients

Transfer to a pre calibrated bottle. Label and dispense

Question 22

What is the wet gum method of making an emulsion?

Answer 22

Add water to acacia gum and quickly trituration to make a mucilage

Add oil in small mounts to mucilage

Trituration thoroughly after each addition until a thick primary emulsion is formed

Stabilise by mixing for several minutes then add other ingredients

Question 23

What are some problems for compounding emulsions?

Answer 23

Phase inversion (if oil and water separate. Often caused by incorrect ratio)

Cross contamination of water/oil caused by equipment not dry e,g, for dry method

Mortar too small and curved, head of pestle too rounded gives insufficient shear. Bigger mortars are better

Excessive mixing at first stage with dry gum method and oil

Diluting primary emulsion too soon and too rapidly

Poor quality acacia

Question 24

What is a suspension?

Answer 24

A disperse system in which one substance is distributed in particulate form throughout the other

Question 25

What happens when a suspension is left standing for a long time?

Answer 25

The solids will separate. However these can often be redispersed on shaking.

Redispersing can be difficult if they form a compacted sediment

Question 26

Why are suspensions used?

Answer 26

When we cannot form a solution due to the active ingredient being insoluble in water

When we need to make a drug in an alternative form for patients who can’t swallow tablets/capsules

Question 27

What are capsules?

Answer 27

Solid preparations for oral administration
Either with a hard or soft gelatin shell
With medicaments enclosed within the shell

Question 28

What are the advantages of capsules?

Answer 28

They give accurate dose
Improved stability
Can be used for powders, non aqueous liquids, solutions, emulsions, suspensions or pastes

Gelatin is clear, tasteless, colourless (or coloured and marked for light protection and identification)
They look good and are easy to swallow
They mask unpleasant tastes

Question 29

Why is a filler needed in dispensing capsules?

Answer 29

Because a balances are limited so we to dilute, usually with lactose

Question 30

When is a glass mortar and pestle used?

Answer 30

If the ingredients are staining

Question 31

How is the dilutent (filler) calculated?

Answer 31

Mitte: 10 + excess 3 = 13 capsules
13 capsules x 10mg hydrocortisone = 130mg
Each capsule should contain 100mg = 1300mg
The lactose filler required is 1300-130 = 1170mg

Question 32

What are the advantages and disadvantages of single dose powders?

Answer 32

\+ small particle size of drug
\+ acceptable to patient
\+ easy to give 
\+ accurate dosing
\+ stable

• may be difficult to swallow
• hard to mask taste
• calculations
• requires time to dispense

Question 33

What are the advantages and disadvantages of capsules?

Answer 33

+ taste easily masked
+ release can be controlled
+ made light resistant

• swallowing is difficult
• not for small children
• animal gelatin in caps

Question 34

How can capsule drug release be tightly controlled?

Answer 34

Some drugs can be commercially formulated with beads to control the release of the drug

Question 35

How are capsules filled?

Answer 35

Wear gloves
Rare the gelatin capsule before filling
Use a dry container e.g. Small glass/plastic bottle

Question 36

What are the storage conditions of capsules?

Answer 36

Shelf life 4 weeks
Cool dry place
Desiccant may be needed

Question 37

What advice should you give to the patient regarding capsules?

Answer 37

Swallow while with water